On 28.04.25 21:57, Suren Baghdasaryan wrote:
On Mon, Apr 28, 2025 at 12:37 PM Lorenzo Stoakes
<lorenzo.stoa...@oracle.com> wrote:
On Mon, Apr 28, 2025 at 07:23:18PM +0200, David Hildenbrand wrote:
On 28.04.25 18:24, Peter Xu wrote:
On Mon, Apr 28, 2025 at 06:16:21PM +0200, David Hildenbrand wrote:
Probably due to what config you have. E.g., when I'm looking mine it's
much bigger and already consuming 256B, but it's because I enabled more
things (userfaultfd, lockdep, etc.).
Note that I enabled everything that you would expect on a production system
(incld. userfaultfd, mempolicy, per-vma locks), so I didn't enable lockep.
I still doubt whether you at least enabled userfaultfd, e.g., your previous
paste has:
struct vm_userfaultfd_ctx vm_userfaultfd_ctx; /* 176 0 */
Not something that matters.. but just in case you didn't use the expected
config file you wanted to use..
You're absolutely right. I only briefly rechecked for this purpose here on
my notebook, and only looked for the existence of members, not expecting
that we have confusing stuff like vm_userfaultfd_ctx.
I checked again and the size stays at 192 with allyesconfig and then
disabling debug options.
I think a reasonable case is everything on, except CONFIG_DEBUG_LOCK_ALLOC and I
don't care about nommu.
I think it's safe to assume that production systems would disable
lockdep due to the performance overhead. At least that's what we do on
Android - enable it on development branches but disable in production.
Right, and "struct lockdep_map" is ... significantly larger than 8
bytes. With that enabled, one is already paying for extra VMA space ...
--
Cheers,
David / dhildenb
